My sister is expecting a house full of visitors in a couple weeks and asked what she can make ahead (even freeze)... to make the food preparation a breeze while they're here. She'd rather play with her grandchildren than spend the day in the kitchen...

I know this one but my mind's a blank right now. One of the best things I do in the summer is stock up on green, seedless grapes, wash them and freeze them in baggies. Frozen grapes are the best snacks for kids and adults in the summer. You can even use them in place of ice in fruit drinks. When I am no longer having a senior moment, I will post more, Trimont.

She could make and freeze taco meat, spaghetti sauce, lasagna, or a baked ziti-type casserole. She could plan on grilling and make, say, a large bowl of potato salad and a large bowl of macaroni salad the day before they arrive, and serve green salad or fruit salad alongside.

__________________The trouble with eating Italian food is that five or six days later you're hungry again. ~ George Miller

Everyone said what I thought already.
Lasagna, pasta sauce, cooked chicken, any cooked meats really.
Also maybe one of those pre-marinated pork loin roasts. They keep in the fridge quite awhile or thaw quickly in cold water, and roast or grill in 45 min or so. Even my pickiest one gobbles those up.

All great ideas. Kids are notoriously fickle about foods so simple is the best way to go. But they do like to help and to make things themselves. A make your own taco night is usually a hit. Also, make your own pizza. You can buy the pre-made crusts and set out lots of toppings and let them have a blast. A big roast with potatoes in the slow-cooker is something most everyone loves, too. I would suggest she stock up on paper plates, cups, and plastic utensils, as well as juice boxes, etc. That way she won't miss her precious time with hours of kitchen clean up.